The cobalt phthalocyanine (CoPc) thin films (300 nm thick) deposited on n-type silicon substrate have been studied using micro-Raman spectroscopy, atomic force spectroscopy (AFM) and I-V measurement. The CoPc thin layers have been deposited at room temperature by the quasi-molecular beam evaporation technique. The micro-Raman spectra of CoPc thin films have been recorded in the spectral range of 1000 cm-1 to 1900 cm-1 using 488 nm excitation wavelength. Moreover, using surface Raman mapping it was possible to obtain information about polymorphic forms distribution (before and after annealing) of metallophthalocyanine (α and β form) from polarized Raman spectra. The I-V characteristics of the Au/CoPc/n-Si/Al Schottky barrier were also investigated. The obtained results showed that influence of the annealing process plays a crucial role in the ordering and electrical conductivity of the molecular structure of CoPc thin films deposited on n-type silicon substrate.
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Diamond electrodes of different morphologies and qualities were manufactured by hot filament chemical deposition (HF CVD) techniques by changing the parameters of diamond growth process. The estimation of diamond quality and identification of different carbon phases was performed by Raman spectroscopy measurements. The effect of diamond quality and amorphous carbon phase content on the electrochemical response of an obtained diamond electrode in 0.5 M H2SO4 as supporting electrolyte was investigated by cyclic voltammetry with [Fe(CN)6]4−/3− as a redox probe. The kinetic parameters such as catalytic reaction rate constant k0 and electron transfer coefficient α were determined. The obtained results show that the analytical performance of undoped diamond electrodes can be implemented just by the change of diamond layers quality.
Przedstawiono zagrożenia spowodowane wyładowaniami elektrostatycznymi (Electrostatic Discharge ESD) w nowoczesnych układach scalonych wykonywanych w technologii CMOS oraz metodologię ich charakteryzowania i kwalifikację. Podano przykłady konkretnych rozwiązań konstrukcyjnych.
EN
The aim of the paper is to provide ESD models and to describe the dangers of Electrostatic Discharges (ESD) in integrated circuits (IC) manufactured in the modern sub-µ CMOS technology.
Przedstawiono budowę, działanie, sposób charakteryzacji i rozwiązania konstrukcyjne układów zabezpieczających przed wyładowaniami elektrostatycznymi (ESD) układów scalonych wykonywanych w technologii CMOS.
EN
The aim of the paper is to provide the structure, functioning and ways of measuring the Electrostatic Discharges (ESD) elements in integrated circuits (IC) manufactured in the modern sub-µ CMOS technology.
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Porous silicon (PSi) layer as gas sensor, based on the change in photoconductivity, photoluminescence and admittance has been presented. PSi layer was prepared by electrochemical dissolution of p-type silicon wafer in HF. Photovoltage curves, photoluminescence spectra (PL) and admittance spectra have been measured in different gas concentrations. Photoconductivity (PC) spectra in vacuum and different gas atmosphere have been compared. Changes of photovoltage intensity curves and change of PC spectra versus concentration of vapour have been observed.
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This paper is concerned with the photoluminescence (PL) study of poly(N-vinylcarbazole) (PVK) thin films deposited on the glass substrate by the dip-coating method. The PL spectra have been measured under steady state excitation (He-Cd laser, 325 nm) in the temperature range from 13 to 300 K. All the samples being studied exhibit strong luminescence in broad temperature range. The main emission PL peak has maximum at 410 nm and is attributed to the excimer emission of PVK. We have observed a small red-shift of this peak with an increase of temperature. In all the films under investigation the thermal quenching of PL has been noticed. This behaviour is determined by the closeness of carbazole groups belonging to neighbouring chains because the interaction between them leads to nonradiative transitions. The PL spectra of PVK thin films annealed under iodine atmosphere have also been investigated. We have observed a decrease of PL for these films. We have concluded that the annealing of PVK under iodine atmosphere induces its degradation.
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The modulated photoabsorption (PA) spectra in Q-band spectral region of copper phthalocyanine (CuPc) thin layer have been investigated using two-channel lock-in phase resolved technique. Combining measurements in-phase and out-phase we determined four different features, which are observed in PA spectra. A detailed analysis of the in-phase and out-phase multicomponent PA spectra and corresponding phase diagram enabled separation of particular components as well as determination of their phase delay angle and corresponding time constants. In the CuPc sample under study, the various components of PA spectrum show different phase shifts, which implies different mechanism giving rise to the photoinduced electric field modulation.
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In this paper we present the photoluminescence emission spectra (PL), photoluminescence excitation spectra (PLE), transmission (TS) and reflection (RS) spectra of tris(8-hydroxyquinoline) aluminum(III) (Alq₃) layers grown by thermal evaporation deposition method. All investigated samples exhibit strong luminescence in the wide temperature range from 13 K to room temperature and for different energies of excitation. In our experiments, we have focused on temperature dependence of photoluminescence. The thermal quenching of PL in the measured samples has been found. We have observed also distinct oscillations from reflection and transmission measurements. The energies of thermal activation estimated by means of configuration coordinate diagram and also the layer thickness and refractive index are presented.
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We investigated photoluminescence (PL) under steady state excitation and photoluminescence excitation (PLE) spectra of thin 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) films deposited on (001)Si substrate with various layer thicknesses grown at different substrate temperatures. The PL and PLE spectra have been measured at various temperatures, ranging from 10 K to 325 K. The PTCDA films exhibit strong luminescence at all mentioned ranges of temperature and for different values of excitation energy. The vibronic structure of PL spectra is clearly resolved at different temperatures. The position of peaks on energy scale depends on the temperature. We have observed a blue-shift of peaks with the decrease in the temperature. In all the investigated samples, the thermal quenching of PL has been observed. Analysis of the temperature dependence of the intensity bands, their position and full width half maximum (FWHM) allowed to find the energy barriers between the excited state and defect state. We propose a schematic potential energy diagram which explains mechanism of PL recombination
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Ternary and quaternary AII BVI mixing semiconductors are very attractive materials for various optical devices. Their optical properties such as the energy gap, linear refractive index, absorption coefficient and lattice constant can be changed with increasing component. For the practical application linear and nonlinear optical characterizations such as the two-photon absorption (TPA), linear and nonlinear refractive indexes are an important aspect. A practical motivation to measure the magnitude of TPA coefficient is that the performance of a device based on nonlinear refraction is strongly affected by the eventual nonlinear absorption. The refractive index and TPA coefficient of Zn1-xMgxSe compounds grown on glass substrates by molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) methods were systematically investigated as a function of Mg composition. The linear optical properties have been studied using transmission, reflection, and photoreflection spectroscopy. The nonlinear optical properties of these materials were investigated by the nonlinear transmission. The energy gap and linear refractive index of these materials change with Mg content, hence the nonlinear optical processes such as TPA and nonlinear refraction index can be modified.
Warstwy krzemu porowatego otrzymano metodą elektochemicznej anodyzacji krzemu typu p. Wykonano pomiary krzemu typu p. Wykonano pomiary przebiegów czasowych fotonapięcia dla różnych długości fal światła wzbudzającego w różnych temperaturach. Pomiary pozwoliły wyznaczyć ruchliwość nośników prądu oraz określić energię głębokich poziomów w strukturze krzemu porowatego.
EN
Porous silicon layers were produced by electrochemical anodisation method. Photocurrent curves at different wavelength of excitation, temperatures and polarization voltages have been measured. Mobility of carriers and deep level energies were determined from photovoltage curves.
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Photoluminescence (PL) spectra and excitation spectra (PLE) (under steady-state conditions), time resolved spectra (PL-TRS) and decay curves of photoluminescence (PL-DC) in micro- and nanosecond range (under pulsed operation) at different temperatures (10 K-room) on anodically etched boron–doped silicon are presented. PLE shows that visible PL is excited by light from UV region. PL and PL-TRS exhibit multiband structure and can be decomposed as a sum of few Gaussians. PL-DCs have multiexponential shape. Relaxation times depend on wavelength of the observation. To explain our results we assumed a model in which the multibarrier structure is formed by larger Si crystallites or wires (quantum well) surrounded by Si crystallites with diameters in the nanometer range (barrier region). The visible photoluminescence originates from radiative recombination between discrete energy levels in a quantum well
Structural and electrical properties of thin diamond films have been studied and discussed in terms of deposition conditions. Diamond films were produced by Hot-Filament CVD (HF-CVD) method modified by doping and electron bombardment of growing surface. Morphological changes were investigated by the scanning electron microscopy (SEM) method reproducing shape of diamond surface. Parameters characterising quality of deposited samples were estimated from Raman scattering measurements. Furthermore, analysis of X-ray scattering data based on Debye-Scherrer equation is described resulting in estimation of grain size and level of stresses of the CVD diamond films. Finally, I-V characteristics of investigated samples are plotted. They are discussed in terms of rectifying properties of such structures caused by distortions of the lattice (Martin's model).
Przedstawiono wyniki badań nad otrzymywaniem cienkich warstw diamentowych, wykazujących właściwości prostownicze. Na podstawie badań za pomocą skaningowej mikroskopii elektronowej (SEM) oraz widm Ramana określono morfologie warstw, udział poszczególnych faz wójtowych oraz rodzaj i wielkość naprężeń występujących w tych strukturach.
EN
The article presents the results of investigations on obtaining of diamond films showing rectifying properties. On the basis of the investigations done by scanning electronic microscopy (SEM) and Raman spectra the morphology of layers has been determined, share of particular carbon phases and kind and magnitude of stresses occurring in the structures.
Influence of different vapours (methanol CH₃OH, isopropanol C₃H₈O, toluene C₆H₅CH₃) on photoluminescence spectra of anodically etched porous silicon measured at room temperature under pulse exciation are presented. Weak changes of the global photoluminescence intensity, distinct changes of spectrum structure and its full recovery after exposure samples to vacuum are observed. To explain our results we assumed, that adsorbed molecules modify propability of nonradiative recombination of the excited carriers on traps located on the surface of silicon crystallites. Presented results and conclussions support quantum confinement as a mechanism of the luminescence of porous silicon.
Deep level transient spectroscopy is used to investigate electrically active traps in porous Si layers prepared by electrochemical etching. Obtained data show that there is a large density of surface states which can interact with molecules of ambient gases. We have treated our samples by the exprosure in air and then moving them back to the vacuum conditions. The DLTS spectrum changes and returns to the steady state conditions after few temperature scans. The shape of DLTS spectrum is independent on the time interval between back to the vacuum conditions and first measurements. The thermal emission energy of observed levels was calculated.
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Linear optical properties of the Zn1-xMgxSe (0 < x < 0,4) alloys have been studied using reflection spectroscopy. The refractive indices of Zn1-xMgxSe epilayers were investigated as a function of Mg composition (0 < x < 0,4). The Sellmeier law is applied to describe the refractive index behaviour as a function of wavelength and magnesium concentration.
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Referat zawiera informacje na temat nowo powstałego Laboratorium Miernictwa Komputerowego. Pracownię tę zorganizowano w Instytucie Fizyki przy Zakładzie Mikroelektroniki Uniwersytetu Mikołaja Kopernika w Toruniu.
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